Thanks for spending time to reply. Again, I appreciate any further advice.
I have already changed the Apple ID in iTunes, but the sticking point is actually the iCloud Apple ID - I can't seem to find anyway of changing this apart from resetting the whole device. The problem with this is that all of her photos and app data are being stored under my iCloud account, and I'd very much prefer her to use her own iCloud service (all her photos appear in my photo stream, which includes hundred of butterflies and my little pony pictures from the apps that an 8 year old would use!), so my iCloud drive gets full, whilst hers remains empty.
I did try a "reset all settings" but on reboot it didn't prompt for an iCloud ID.
I've tried playing around with iTunes as well - if I go to Account Info> Manage Devices, I can see a list of devices associated with my Apple ID (9 in total!) It says computers and devices can be associated with a different Apple ID once every 90 days... I've removed the iPad that I believe is my daughter's (and I also tried my wife's), but this makes no difference either - iCloud is still associated with my ID.
I also went to www.icloud.com and I can see all the devices associated with my iCloud account - but can't change anything.
My daughter has also inherited my wife's old iPhone5, which I did a full reset for and successfully associated with her iCloud account - as it was a new device to her this wasn't a problem... However, her iPad has lots of game progress (like my little ponies) that would be lost with a full reset.
Anybody have a solution? Thanks in advance.